The Effect of Carbetocin on Cardiac Repolarization: A Randomized, Placebo‐ and Positive‐Controlled QT / QTc Study in Healthy Adults

ABSTRACT

Carbetocin is an oxytocin receptor agonist used for postpartum hemorrhage prevention. While oxytocin is known to transiently prolong the QT/QTc interval, robust QTc data for carbetocin are limited. Carbetocin is known to elevate HR, which can impact QTc analyses; thus, a dose that did not overly elevate HR was important to select. This randomized, placebo‐ and positive‐controlled trial evaluated the effect of a single intravenous infusion of a supratherapeutic dose (650 μg) of carbetocin over 45 min on cardiac repolarization in healthy adults ( N  = 42). Continuous cardiodynamic ECGs were recorded from 45 min before through 24 h after dosing. The primary endpoint was placebo‐corrected change from baseline in QT interval (ΔΔQTc) using the most appropriate heart rate (HR) correction method. The primary analysis was based on exposure‐response modeling of the relationship between carbetocin plasma concentrations and ΔΔQTc, to identify an effect ≥ 10 msec at the high clinical exposure. During intravenous infusion of carbetocin, the mean HR change from baseline reached a maximum of 16.7 bpm. Multiple correction methods for HR were assessed, and the placebo‐corrected, optimized, individualized heart rate–corrected QT interval (oQTcI) was found to be adequate. The estimated mean placebo‐corrected oQTcI change from baseline was 4.5 msec (90% CI: 3.4, 5.6) at the high clinical exposure level of 12.4 ng/mL following a single intravenous infusion of 867 μg/h carbetocin. Exposure‐response models for carbetocin established no predicted QTc prolongations of clinical or regulatory concern (≥ 10 msec) at the high clinical exposure level.

Trial Registration: ClinicalTrials.gov Registration: NCT05924321